Hydraulic transmission gear



Rge. 21,035

March 28, 1939. H. FGTTENGER HYDRAULIC TRANSMISSION GEAR Original Filed April 4. 1934 Reiuued Mar. 28, 1939 UNITED STATES,

PATENT OFFICE HYDRAULIC TRANSMISSION GEAR Hermann Fiittinger, Berlin-Wilmersdorf, Germany 6 Claims.

.In the well-known hydraulic transmission gears or turbo-transformers which consist' of pump wheels, turbine wheels and guide wheels the speed of the turbine wheels, viz. the secondary wheels. changes within wide limits in cordance with the resistance to be overcome.

, e speed of the pump wheels being kept constant, the normal speed and the highest emciency will be obtained with a definite torque of the turbine, viz. the so-called normal torque of the turbine wheels. When the speed of the turbine is reduced, for instance at starting or by hard braking, the torque of the turbine increases by itself and the amount of increase willbe dependent on the number, the radii and the blading of the turbine wheels and the guide apparatus as well as of the type of the pump. As the speed of the turbine increases, the torque inversely decreases until in the case of no-load work the torque has dropped to zero. When hydraulic transmissions are built in, e. g. into 2111- tomobiles, various tractive efforts; that is var ious torques must be successively overcome.

Consequently the speed ofthe turbine adjusts itself according to the torque to be overcome and thus also the running speed of the car is automatically adapted without steps to the amount attainable. Therefore the decrease of the speed is automatically accompanied by an in- 0 crease of the torque.

The hydraulic transmission gears hitherto built were as a-rule intended for ships and similar purposes where an increase of torque forstarting would be unnecessary anduseless. The only intention was to arrive at a maximum efflciency with the normal run. 0! course, also in this instance a corresponding increase of the torque took place at starting, viz. with the minimum of angular speed, and in such a way that the starting torque amounted to about double the normal torque and the no-load speed to about double the normal speed oi'the turbine. The curve of the efficiency was similar to a para bola the vertex of which coincides with the point of normal speed.

etc. it is desirable that the tractive effort, viz. the torque be increased atstarting as much as possible by a suitable design of the hydraulic system. The ideal shape of the speed curve would be the so-called ideal tractive-eifort hyperbole." which, however, could he arrived at only in the case of gears free of loss and would result at an infinitely large tractive effort in the start."

The ideal tractive -efiort hyperbola can, of

In the case of land vehicles, lifting machinery.

course, not be attained in a transmission gearpractically built, although it would be the-most ideal design for the use on land vehicles etc.

Now, it is an object of the present invention to provide for a hydraulic transmission gear 5 which is particularly suited for land vehicles, lifting machinery and the like and shows a torque or tractive effort curve as favorable as possible, that is a torque curve which lies between the ideal tractive-efio rt parabola and the straight- 0 line increase of torque actually'prevailing in the hydraulic transmission gears already known.

The novel-means found out for the solution of this problem and further improvements of the hydraulic transmission gear as detailedly 15 specified in the following description are the subject matter of the present invention. The accompanying drawing shows several embodiments of the invention, and in them 7 Fig. 1 is a chart-of the dependencies prevail- 20 ing between torque, speed and efliciency in prior transmission gears, this chart explaining the object of the'present invention.

Fig. 2 is a further chart and shows-the circumferential velocity at the outlet of the turbine 25 as plotted. against the relative discharge velocity and the outlet angle.

Fig. 3 is a. partial section through a hydraulic transmission gear according to the invention.

Fig. 4'is a partial section through Fig. 3 ac- 3o cording to the line IVIV and seen in the direction of the arrows.

5 shows the right part of Fig. 3 and illustrates another embodiment of the guide blades,

and

Fig. 6 is a section through Fig. 5 according to the line VIVI seen in the direction of the arrows.

In the chart, Fig. l, the abscissae represent the angular speeds and the ordinates the torques. 40

With a normal speed 'nnorm the normal torque is Mn. 'When the speed is decreased, the torque increases; when, however, the speed rises, the torque drops.

In the well-known earlier constructions of the 45 inventor the latter used turbines with an admission directed to the interior (Francis type) with three to five turbine stages or there were used two or three complete turbine circuits with the same direction of rotation. This arrangement resulted in torque curve M designated by I in Fig. 1, viz. in a straight line. At the start the. torque was about double as high as the normal torque Mn and when'running without load the u speed m. was aboutdouble as high as the normal speed.

Another well-known transmission gear (the Rieseler gear U. S. Patent No. 1,727,903) has 1 a torque line designated by III in Fig. 1, when running in the hydraulic circuit 'with a twostage turbine and a guide device alternately immobilized by hard braking or running free.

. In this instance the starting torque is even lower so that this arrangement is still less suitable for landvehicles, lifting machinery etc.

In the other transmission gears known, for instance the Lysholm-Ldungstrom gears (U. 8. Patent No. 1,900,120) a great many turbine steps, but at least three stages with radial blading are used and particularly steep outlet angles are provided for. Also in that instance the intention was to fully remove the tangential component cu of the absolute velocity of flow prior to the return of the water into the pump (socalled vertical admission). This resulted in a curve like that' designated by II in Fig. 1 and which ls-much more advantageous than curve I. It lies between the latterand the dotted ideal tractive-effort hyperbola .as' plotted in Fig. 1 which also comprises the parabolic curve of the efllciency 1 In order to obtain torques similar to those represented by curve II, Coats (U. 8. Patent 1,760,397) further made use of a guide apparatus which comprises one fixed guide blade rim and four movable guide-blade rims, which are either allowed to freely revolve or the blades of which can freely turn. This turbine was of the Francis type with a small inlet radius anda large outlet radius.

It is obvious from this that as faias it was possible to arrive at a torque curve lying between the straight. torque line I and the ideal perbole, it was necessary to make use of very intricate designs.

Now, the inventor has found out that degrees of increase of the tractive effort, viz. torque curves like thoseshown by II and which were attained, so far, only with at least three turbine stages (six wheels) or with oneflxed and four revoluble guide blade rims (seven wheels), can

' lowing features, namely:

already be arrived at with one single turbine stage in one circuit comprising three fixed wheels,

accordingly with a fraction of the means hitherto necessary for that p pose.

This effort absolutely unexpected and diametrically opposed to the notion of other specialists is, according to the invention, substantially ob tained by the essential combination of the fol- (a) In the cycle there is disposed in combination with a pump wheel only the one secondary wheel the inlet radius of which does not exceed the outletradius (consequently no Francis turbines) blades continually operative while the other rim carries supplementary blades used for slowancircumference at the outoutlet angles being smaller '01. about the same magnitude.

or/and the secondary wheel consist 'of two rims one of which carries gular speeds and which at higher angular speed are withdrawn from action. The totality of these features results in'the surprising progress here disclosed. a

The addition hitherto usual of centripetal turbines of the Francis type (inlet radius larger than outlet radius) to the pump which works here with very variable delivery heads (and quantities of water sensibly impairs e. g. the increase of. torque of turbines showing the features (a) or (b) +(c) The great increase of the momentum intended by. the invention cannot having steep blade angles or blades insuiliciently thickened.-

The substantially thickened blade heads, per se known in water turbines, serve here the special purpose of suiiiciently safely providing for the highly increased torque (particularly during the start) by means of rim, in away which is satisfactory hydraulically and with respect to mechanical strength, whereas this torque was distributed over 2 or 3 turbine rims in the earlier types (U. S. Patent 1,900,120)

The invention is further based on the following important finding:-Occasionally it had been observed on the old Foumeyron turbines (outlet radius larger than inlet radius) that the torque characteristic was slightly curved upward towards the hard-braking point (see Escher-Dubs Die Theorie'der Wasserturbinen", 3rd edition, page 2 and pages 171-174). These turbines built into rivers, however, work under other hydraulic conditions than the present transmission gears (torque transformers) :-In spite of the angular speed varying between normal and zero the height of fall of the river remains constant. in the self-contained transmission gear, however, not only the head of the turbine but also the quantity or water change sensibly, since in the short-circuited circuit a reaction directly takes place onthe pump which does not furnish any constant head. of sensibly varies with the quantity of water delivered (cf. the Q-H characteristic). The quantity of water, however, adjusts itself in such.a way that the total resistances in the pump, turbine and guide apparatus (friction, shocks and head utilized) are overcome.

The finding that theparticular application-of smaller inlet radii with larger or, at the most, equal outlet radii of the turbine is, among other things, decisive forsurprisinglyhigh increasesof the torque under the particularly intricate conditions of flow in the present transmission gears, represents a substantial progress in transmission engineering, especially as it permits of doing.

away with the prejudice that the Francis turbine (with larger inlet and smaller outlet radii), which is advantageous for the maximum emciency, is

' also superior. for the spontaneous increase of the tractive effort in the Fig. 2 shows one of the usual turbine triangles in which according to the invention the circumferential velocity u and the velocity of flow (here the relative velocity at the channel outlet) are hard braking w is sensibly incr The blade angles s: are then smaller than 35 de rees, while in the case of larger angles unsatisfactory ratios u/w would be the result (viz. too small it as compared with w). The blade may e. g. have the rounded shape shown which is per se known in steam tm'bines, propellers, pumps and water turbines, it may, however, also be pointed in a preferably one single turbine Inthecaseoi! be attained with gear? water but a head which very suitable manner but at any rate it must have substantially thickened inlet ends.

In the embodiment shown byFlg. 3 the primary shai't l carrles'the pump wheel 3, which delivers the water intothe coaxial turbine or secondary wheel 33, 33' which is coupled with the secondary shaft 3 by means of the disc 5.

From here the water flows through a blade'less channel 33 to the guide rims 3|, 3| disposed oppomte to the secondary wheel and finally back through the bladeless channel 40 into the pump.

The guide rim 3| is supported by a carrier 33 which can, as desired, rotate on or with the primary shaft I or may be immobilized against rotating by the brake 38.

At the maximum speed the guide device may be freed by a release of the'hard braking at 33 so that the circuit is converted into a soft hydraulic clutch. At the maximum running speed the latter may be replaced by a rigid coupling consisting in a tooth or friction clutch 35 so that the emciency 1 is raised to practically 100% andall means today available for the increase of tractive effort and. efficiency are combined within a minimum of space.

For increasing the tractive effort and at the same time the efllciency the guide device consists of two rims 3|, 3| the one of which 3| being adapted to be inserted into the circuit or withdrawn into the chamber 33 according to the speed desired in an axial' direction into the same circuit.

According to the invention, this measure can be further improved by not only a second guide apparatus but also a second turbine wheel30' being inserted in a suitable way, e. g. also. by an axial displacement into and from the chamber 34. Then a turbine wheel adapted'to the particular running speed will correspond to each guide apparatus (Fig. 3).

In some instances this will, however, present the disadvantage that the mechanical connection between the casing and the core 33 of the circuit or other'corresponding members is lost so that special supporting blades leaving the twist substantially unchanged must be used in order to reestablish this connection.

This inconvenience by itself not essential can be overcome according to the invention by the particular guide blades of the guide device and/ or the blades of the turbine being each divided into an inlet and an outlet part the latter ofwhich is continually used and at the same time connects the outside wall 5 and the internal core 33 of the circuit with one another while the inlet part is so shaped that it completes the outlet part suited for high and medium speeds only, to 'a kind of hooked blade which is on the contrary adapted to low'speeds and particularly to the development of maximum tractive effortsv for starting.- By this arrangement the double or multiple branched circuits for transmission gears as disclosed by earlier patents of the inventor are so to speak combined into a single circuit so that an essential simplification and improvement of the set is obtained, the more so as it was found out that the pump in any instance common to the latter can show definite properties which are hydraulically advantageous for either running speed.

Fig. 4 shows such special blades consisting each of an inlet part 3| and an outlet part 3|. and which are suited for the change both of the guide device and of the turbine impellers. 3| e. g. has the typical shape 01' the reaction blades corresponding to high and medium speeds of the turbine while the combination of 3| and 3| results in an advantageous action or impulse turbine blading.

According to a further embodiment of the invention shown in Figs. 5 and 6 the supplementary blades are so arranged as to partially overlap the thickened heads of the continually operative blades 3|; The rim of these supplementary or split blades 31 may be inserted and withdrawn by an axial displacement, slots ll being provided for this purpose in the carrier-36.

In Fig. 3, 3| is the rim continually used in' the guide devicewhile 3| is the supplementary rim which is adapted to disappear in the chamber 33 connected with the stationary guide device. The displacement is e. 8. accomplished in the well-known way by the hydraulic pressure in the gear itself as illustrated and described in the inventors Patent No. 1,199,361. This feature is long known and therefore not a subject matter of the present invention. The supplementary rim 3| is naturally disposed in the direction of flow in front of the outlet rim 3| continuously used, viz. in the present instance at a larger radius than 31.

In thesame way the turbine outlet rim 30 may also, for the development of the maximum starting tractive efforts and efliciencies, be rigidly connected with the casing 5 and the core 33 while in the case of medium and high running speeds the supplementary rim 30' can disappear into the chamber 34 of the secondary runner.

The rim-receiving chambers 32 and 34 may be disposed as desired either within the core or on the outside of the casing.

A further advantage of the invention consists in that, if desired, ity is possi le to obtain an additional braking effect by means of the hydraulic gears. This effect is particularly desirable in the case of long descents or when the driver encounters an unexpected obstruction so that braking with any possible means imposes itself. After having reached a certain speedthe hydraulic gear will as a rule be used as a uplin or the driver will have the car to run with a direct mechanical clutch engagement so that according to the above statement it would be necessary to render the guide device inoperative in the circuit either by free running or by a withdrawal from the circuit.

When new with such a speed the secondary shaft is to be braked, the guide wheel is inserted again by being immobilized or returned into the circuit. In the same way in which initially a sensible increase of the torque was obtained in the start, the guidedevice being inserted, viz. the transition from the coupling to the torque transforming effect, will result in a powerful braking action on the secondary part. A particularly powerful braking effect is obtained by the primary shaft, for instance the engine, being braked to stoppage. In either instance the hydraulic gear acts as a water brake.

The essential features of the invention as charing are also readily appliable to-embodiments of turbines, pumps and hydraulic transmission gears in a general way.

I claim: l

1'. A hydraulic transmission gear for an intensified automatic torque increase at the start, comprising a primary pump wheel, only one secelceed the outlet radius, and the blades of which, substantially thickened at the inlet and eventually rounded oil, and formed with flat anglesp:

with the circumference at the outlet whereby the tinually operative while the other rim carries supplementary blades for slow angular speeds of the secondary wheel, and means for rendering the supplementary bladw inoperative at higher angular speeds.

s. A hydraulic gear form intensiiied automatic torque increase at the start,

a primary pump wheel, only one secondary wheel the inlet radius of which does not exceed the outlet radius, and the blades of which, substantially thickened at the inlet and eventuallyroundedoihfonnflatanglespzwiththe circumference at the outlet whereby the relative discharge velocity (in) and the peripheral velocity (its) at that point are of substantially, the same magnitude at the normal angular speed oi maximal eiiicien'cy (am), a chamber connecting the outlet of the secondary wheel with the inlet oi the pump wheel, guide means operable in said chamber, the secondary wheel consisting of two rims one of which carries'blades' continually operative while the other rim carries supplementary blades operative for slow angular speeds of the secondary wheel and means for withdrawing the supgflementary blades from action at higher angular speeds.

3. A hydraulic ton gear according to claim 1, in which also the secondary wheel consists of two rims, one of which carries blades continuallyoperative while the other rim carries supplementary blades for slow angular speeds of the secondary wheel and which at higher angular speeds are withdrawn from action byaxial displacement.

4. Ahydraulic gearaccording to claim 1 in which the supplementary blades being 50 so arranged as to overlap the thickened heads of the continually operative blades.

ondary wheel the inlet radius of which does not 5.'A lwdraulic ton gear for an intensifled automatic torque increase at the start. comprising a primary pump wheel, a secondary wheel, the inlet radius of which does not exceed the outlet radius, and the blades of which, substantially thickened at the inlet and eventually rounded oil, form flat angles p: with the circumierence at the outlet whereby the relative discharge velocity (in) and the peripheral velocity (its) at that point are of the substantially same magnitude at the normal angular speed of maximal efllciency (nnorm) a chamber connecting the outlet of the secondary wheel with the inlet of the pump wheel, guide means operable in said chamber and consisting of two rims one of which carries guide blades continually operative while the other rim carries supplementary blades for slow angular speeds of the secondary wheel and means for rendering the supplementary blades inoperative at higher angular speeds and the guide means being arranged on the side of. the

, circuit opposite to the side of the secondary wheel.

6. A hydraulic transmission gear for an intensified automatic torque increase at the start, comprising a primary pump wheel, a secondary wheel, the inlet radius of which does not exceed the outlet radius, andthe blades of which, substantially thickened at the inlet and eventually rounded off, form flat angles 52 with the circumierence at the outlet whereby the relative discharge velocity (10:) and the peripheral velocity (its) at that point are of the substantially same magnitude at the normal angular speed of maximal emciency (nnorm) a chamber connecting the outlet of the secondary wheel with the inlet of the pump wheel, guide means'operable in said chamber and consisting of two rims one of which carries guide blades continually operative while the other rim carries supplementary blades for slow angular speeds oi the secondary wheel and means for rendering the supplementary blades inoperative at higher angular speeds and the guide means being arranged on the side of the circuit opposite to the side of the secondary wheel, anda bladeless channel provided be-v tween the outlet of the turbine wheel and the inlet o! the supplementary guide blades.

mrawimr- Formosa. 

